The invention relates to an electromagnetically actuated injection valve of the kind used in electronically controlled injection devices for supplying controlled-ignition engines. More particularly, the invention relates to an injection valve which controls the amount of fuel sent to the engine by opening a constant-section discharge aperture for a given time, which is a fraction of a working cycle of the engine.
Valves of this kind are known.
Valves at present in production pose substantially the following problems:
(1) In order to reduce consumption and pollution, the discharge aperture must be formed in the intake manifold so that the fuel is kept as far as possible away from the walls thereof.
(2) The closure means must have longitudinal dimensions appropriate to the design of the intake manifold but its mass must be at a minimum, in order to reduce the effects of mechanical inertia on the travel time of the closure means.
(3) Friction between the guide surfaces of the closure means must be reduced to a minimum, in order further to reduce the travel times and increase the life of the parts subjected to friction.
(4) The amount of fuel injected per working cycle of the injector must be limited, but only by dimensioning the discharge aperture, so as to eliminate abrupt changes in the trajectory through the supply portion, wich is upstream of the discharge aperture, and also so that the apertures can have relatively small dimensions, since this increases the atomizing effect on the fuel.
(5) It must be possible to construct the injectors industrially at moderate cost and
(6) The range of dimensions of the metering parts in series production must be limited, the fuel delivery being metered only by the discharge aperture defined at the end of the nozzle.